Thanks to Caroline Morris here is the URL for the tubes.
http://shop.woodcraft.com/woodcraft/product_family.asp?family%5Fid=1780
 
They have 2 sizes, 4" & 2.5".  They are 10' long.
 
Woodcraft
210 Wood County Industrial Park
PO Box 1686
Parksburg, WV 26102-1686
 
1-800-225-1153
 
The URL takes you right to the page you need.
 
Hug the Fuzz
Lynn
[Posted in FML issue 2925]